Marine engine exhaust system with cooling arrangement

FIELD OF THE INVENTION

p-0002The present invention relates generally to an exhaust system for an inboard marine engine. More particularly, the present application involves a marine engine exhaust system for use with a twin head engine that has a cooling arrangement.

BACKGROUND

p-0003Marine engines used to power watercraft can be generally classified as either being an inboard, outboard, or stern drive. An inboard engine is located inside of the watercraft and poses certain design challenges. For example, an inboard engine is generally confined to a small space in which air flow is limited. Limitations of air flow around the engine require a sufficient cooling arrangement be in place in order to handle heat generated during use. Further, as the engine is operated in a marine environment precautions must be taken in order to prevent water from finding its way inside of and consequently damaging the engine.

p-0004One type of inboard marine engine employed on watercraft is a twin head engine. This type of engine features cylinders that are located on opposite sides of the engine that generate exhaust gases upon firing. Manifolds are commonly employed in order to channel the exhaust gases into a single stream on one side of the engine and into a single stream on the opposite side of the engine. The two exhaust gas streams may then be routed to a discharge point from which the exhaust gases can exit the watercraft. Alternative arrangements are known in which the two separate exhaust gas streams are combined into one stream and subsequently routed to a discharge point. The two manifolds are designed in order to inhibit the movement of water through the manifolds and into the inboard engine.

p-0005The gas streams can be transferred from the manifolds in jacketed conduits. A cooling fluid, such as water or antifreeze, is transferred through the jacketed conduits and kept separate from the gas streams in order to draw heat from the gas streams and cool the exhaust system. The cooling fluid is inserted into the conduits proximate to the manifolds and flows in the same direction through the conduits as does the exhaust gases. It may be the case that cooling fluid is not present at certain locations of the conduits. For example, the top of the conduits may not have cooling fluid present due to the fact that the cooling fluid is drawn by gravity down to the bottom of the conduits as the cooling fluid flows therethrough. Further, the orientation of the conduits themselves may be provided so that certain portions are void of cooling fluid. The absence of cooling fluid at certain locations leads to the formation of hot spots on the conduits at these locations. Hot spots may result in the burning of individuals should they come into contact therewith. Further, hot spots may cause a fire aboard the watercraft, and hot spots could lead to a weakening of components of the exhaust system which may cause it to fail. As such, there remains room for variation and improvement within the art.

SUMMARY

p-0006Various features and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned from practice of the invention.

p-0007One aspect of one exemplary embodiment provides for a marine engine exhaust system that includes first and second manifolds. A first corner is in fluid communication with the first manifold so that a first gas exiting the first manifold is transferred into the first corner. The first corner has a first corner cooling fluid passageway. A second corner is in fluid communication with the second manifold so that a second gas exiting the second manifold is transferred into the second corner. The second corner has a second corner cooling fluid passageway. A crossover is in fluid communication with the first corner and the second corner so that the first gas exiting the first corner is transferred into the crossover and so that the second gas exiting the second corner is transferred into the crossover. The crossover has a crossover cooling fluid passageway configured for receiving cooling fluid. The crossover cooling fluid passageway is configured for allowing cooling fluid to be transferred into the first corner cooling fluid passageway and the second corner cooling fluid passageway.

p-0008Another aspect of an additional exemplary embodiment includes a marine engine exhaust system as immediately discussed in which the cooling fluid is water.

p-0009A further aspect of another exemplary embodiment exists in a marine engine exhaust system as described above in which the first manifold has a first catalyst for treating the first gas. Also, the second manifold has a second catalyst for treating the second gas.

p-0010An additional aspect includes an exemplary embodiment of a marine engine exhaust system as mentioned above in which the crossover cooling fluid passageway is oriented with respect to the first corner cooling fluid passageway and the second corner cooling fluid passageway. The crossover cooling fluid passageway is oriented so that cooling fluid fills the crossover cooling fluid passageway before filling at least substantially all of the first corner cooling fluid passageway and the second corner cooling fluid passageway.

p-0011Also provided in accordance with another aspect of one exemplary embodiment is a marine engine exhaust system as previously mentioned that has a heat exchanger. The cooling fluid is antifreeze. The first corner cooling fluid passageway and second corner cooling fluid passageway are configured to allow the antifreeze to be transferred therefrom and into the heat exchanger in order to be cooled. The heat exchanger is configured to allow the antifreeze to be transferred therefrom and to an engine in order to cool the engine.

p-0012An additional aspect of one exemplary embodiment includes a marine engine exhaust system as previously discussed in which the first gas and second gas are maintained separate from one another in the crossover. Also included is an elbow in fluid communication with the crossover so that the first gas exiting the crossover is transferred into the elbow. The second gas exiting the crossover is likewise transferred into the elbow. The elbow is configured to allow the first gas and the second gas to merge with one another.

p-0013A further aspect of another exemplary embodiment resides in a marine engine exhaust system that has a first manifold and a second manifold. A first conduit is in fluid communication with the first manifold so that a first gas exiting the first manifold is transferred into a first gas passageway of the first conduit. The first conduit has a first cooling fluid passageway. A second conduit is in fluid communication with the second manifold so that a second gas exiting the second manifold is transferred into a second gas passageway of the second conduit. The second conduit has a second cooling fluid passageway. Cooling fluid is transferred through the first cooling fluid passageway so as to have a direction of flow through the first conduit opposite to the direction of flow of the first gas through the first gas passageway of the first conduit.

p-0014An additional exemplary embodiment includes a marine engine exhaust system as immediately discussed in which cooling fluid is transferred through the second cooling fluid passageway. The cooling fluid has a direction of flow through the second conduit opposite to the direction of flow of the second gas through the second gas passageway of the second conduit.

p-0015Another aspect of a further exemplary embodiment is present in a marine engine exhaust system as mentioned above that further has a third conduit in fluid communication with the first conduit and second conduit. The first gas exiting the first conduit and the second gas exiting the second conduit merge in the third conduit. Cooling water is merged with the first gas in the first conduit and with the second gas in the second conduit before the first gas and the second gas merge in the third conduit.

p-0016Also provided in accordance with another aspect is a marine engine exhaust system as previously mentioned that further includes a heat exchanger. The cooling fluid is antifreeze. The first cooling fluid passageway and second cooling fluid passageway are configured to allow the antifreeze to be transferred therefrom and into the heat exchanger to be cooled. The heat exchanger is configured to allow the antifreeze to be transferred therefrom and to an engine in order to cool the engine.

p-0017An additional aspect exists in an exemplary embodiment of a marine engine exhaust system that has a first corner configured for the transfer of a first gas therethrough. The first corner has a first corner cooling fluid passageway. A second corner is configured for the transfer of a second gas therethrough. The second corner has a second corner cooling fluid passageway. A crossover is in fluid communication with the first corner and second corner so that the first gas exiting the first corner is transferred into the crossover and so that the second gas exiting the second corner is transferred into the crossover. Cooling fluid is located in the first corner cooling fluid passageway and flows therethrough. The direction of flow of the first gas through the first corner is different than the direction of flow of the cooling fluid through the first corner.

p-0018Another aspect of a further exemplary embodiment is found in a marine engine exhaust system as immediately mentioned in which cooling fluid is located in the second corner cooling fluid passageway and flows therethrough. The direction of flow of the first gas through the first corner is different than the direction of flow of the cooling fluid through the first corner. The direction of flow of the cooling fluid through the first corner is opposite to the direction of flow of the first gas through the first corner. The direction of flow of the cooling fluid through the second corner is opposite to the direction of flow of the second gas through the second corner.

p-0019These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth more particularly in the remainder of the specification, which makes reference to the appended Figs. in which:

<figref idrefs="DRAWINGS">FIG. 1</figref> is a perspective view of a marine engine exhaust system in accordance with one exemplary embodiment.

<figref idrefs="DRAWINGS">FIG. 2</figref> is a schematic circuit view of the marine engine exhaust system of <figref idrefs="DRAWINGS">FIG. 1</figref>.

<figref idrefs="DRAWINGS">FIG. 3</figref> is a cross-sectional view showing the corners and crossover of the marine engine exhaust system of <figref idrefs="DRAWINGS">FIG. 1</figref>.

<figref idrefs="DRAWINGS">FIG. 4</figref> is a schematic circuit view of a marine engine exhaust system in accordance with another exemplary embodiment.

<figref idrefs="DRAWINGS">FIG. 5</figref> is a perspective view of a marine engine exhaust system in accordance with yet another exemplary embodiment.

<figref idrefs="DRAWINGS">FIG. 6</figref> is a schematic circuit view of the marine engine exhaust system of <figref idrefs="DRAWINGS">FIG. 5</figref>.

<figref idrefs="DRAWINGS">FIG. 7</figref> is a cross-sectional view showing the corners and crossover of the marine engine exhaust system of <figref idrefs="DRAWINGS">FIG. 5</figref>.

<figref idrefs="DRAWINGS">FIG. 8</figref> is a cross-sectional view of the riser and elbow of the marine engine exhaust system of <figref idrefs="DRAWINGS">FIG. 5</figref>.

p-0029Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the invention.

DETAILED DESCRIPTION OF REPRESENTATIVE EMBODIMENTS

p-0030Reference will now be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, and not meant as a limitation of the invention. For example, features illustrated or described as part of one embodiment can be used with another embodiment to yield still a third embodiment. It is intended that the present invention include these and other modifications and variations.

p-0031It is to be understood that the ranges mentioned herein include all ranges located within the prescribed range. As such, all ranges mentioned herein include all sub-ranges included in the mentioned ranges. For instance, a range from 100-200 also includes ranges from 110-150, 170-190, and 153-162. Further, all limits mentioned herein include all other limits included in the mentioned limits. For instance, a limit of up to 7 also includes a limit of up to 5, up to 3, and up to 4.5.

p-0032The present invention provides for a marine engine exhaust system <b>10</b> that can be used on a twin head inboard engine <b>46</b> in a watercraft. The marine engine exhaust system <b>10</b> may include a pair of conduits <b>52</b> and <b>58</b> extending from a pair of manifolds <b>12</b> and <b>14</b> of the engine <b>46</b> through which exhaust gases <b>18</b> and <b>24</b> are transferred. Cooling fluid <b>32</b> can be transferred through the conduits <b>52</b> and <b>58</b> in order to provide cooling to the system <b>10</b>. The cooling fluid <b>32</b> can be introduced in such a manner that the cooling fluid <b>32</b> flows in a direction opposite to the direction of flow of the gases <b>18</b> and <b>24</b> through the conduits <b>52</b> and <b>58</b>. The conduits <b>52</b> and <b>58</b> can be arranged so that the cooling fluid <b>32</b> fills the low points of the conduits <b>52</b> and <b>58</b> first through gravity and then eventually fills the remaining portions of the conduits <b>52</b> and <b>58</b> before being transferred therefrom. Arrangement of the conduits <b>52</b> and <b>58</b> in this manner reduces the occurrence of hot spots thereon as cooling fluid <b>32</b> is able to find its way into a greater portion of the conduits <b>52</b> and <b>58</b>.

p-0033<figref idrefs="DRAWINGS">FIG. 1</figref> shows a marine engine exhaust system <b>10</b> in accordance with one exemplary embodiment of the present invention. The marine engine exhaust system <b>10</b> is shown being used in conjunction with an engine <b>46</b> that is an eight cylinder twin head marine engine. It is to be understood, however, that other exemplary embodiments exist in which the engine <b>46</b> may be variously configured. A first manifold <b>12</b> is located on one side of the engine <b>46</b> and is in communication with the cylinders of the engine <b>46</b> located on this side. The first manifold <b>12</b> is used to transport exhaust gas from the engine <b>46</b> and typically includes internal features, such as runners, that are used to more easily channel the gas from the individual cylinders to a single stream. The manifold <b>12</b> may also include additional internal features, such as damns, that act to catch water and prevent it from regressing back into and damaging the engine <b>46</b>.

p-0034The first manifold <b>12</b> may include a first catalyst <b>36</b> in accordance with certain exemplary embodiments of the present invention. The first catalyst <b>36</b> functions to reduce pollutants in a first gas <b>18</b> passing therethrough from the engine <b>46</b>. An oxygen sensor <b>38</b> may be included in the first manifold <b>12</b> and positioned to acquire data regarding the first gas <b>18</b> before entering the first catalyst <b>36</b>. An additional oxygen sensor <b>40</b> is located after the first catalyst <b>36</b> and monitors the first gas <b>18</b> exiting therefrom. The functionality of the first catalyst <b>36</b> can be monitored and information retrieved can be used to modify the running of engine <b>46</b> or other components of the watercraft. The first catalyst <b>36</b> can be of any type used with engine exhaust systems. Typically, the first catalyst <b>36</b> works best if the first gas <b>18</b> is both hot and dry. In fact, water may damage the first catalyst <b>36</b>, oxygen sensor <b>38</b> and oxygen sensor <b>40</b> in certain embodiments thus making water control at this portion of the marine engine exhaust system <b>10</b> desirable.

p-0035A second manifold <b>14</b> is located on the side of engine <b>46</b> opposite that of the first manifold <b>12</b>. The second manifold <b>14</b> receives exhaust gases from the cylinders located on the side of engine <b>46</b> opposite the first manifold <b>12</b>. The second manifold <b>14</b> may be provided in a manner similar to the first manifold <b>12</b> as previously discussed and a repeat of the features and functionality is not necessary. Additionally, a second catalyst <b>42</b> can be provided in order to treat a second gas <b>24</b> transferred from the second manifold <b>14</b>. The second catalyst <b>42</b> along with oxygen sensors <b>41</b> and <b>45</b> can be provided as previously discussed with respect to the first catalyst <b>36</b> and oxygen sensors <b>38</b> and <b>40</b> and repeating their features and functionality is likewise not necessary. Although described as employing catalysts <b>36</b> and <b>42</b>, it is to be understood that other embodiments of the present system <b>10</b> are possible in which either one of or both of the catalysts <b>36</b> and <b>42</b> and associated oxygen sensors <b>38</b>, <b>40</b>, <b>41</b> and <b>45</b> are not present. Further, catalyst <b>36</b> may be made of different materials or may have a construction different than catalyst <b>42</b> in accordance with certain exemplary embodiments.

p-0036The engine <b>46</b> in the exemplary embodiment of <figref idrefs="DRAWINGS">FIG. 1</figref> makes use of a raw water cooling system. A raw water system employs water as the cooling fluid <b>32</b> and obtains this water from the body of water into which the watercraft is deployed. The water is routed to various portions of the engine <b>46</b> in order to draw heat therefrom and hence effect cooling. A thermostat <b>84</b> is shown and is used to regulate the temperature of the engine <b>46</b> and may also be used, if desired, to regulate the temperature of the manifolds <b>12</b> and <b>14</b>. In use the majority of water passes through the thermostat <b>84</b> and is routed to various portions of the engine <b>46</b> while some water is directed from thermostat <b>84</b> into a by-pass line <b>92</b> and into a crossover <b>28</b> of the marine engine exhaust system <b>10</b>. Upon detecting the temperature of water flowing therethrough, the thermostat <b>84</b> can regulate the quantity of water transferred into the by-pass line <b>92</b> in order to adjust the temperature of the cooling water <b>32</b> and in turn regulate the temperature of any one of or all of the engine <b>46</b>, first manifold <b>12</b> and second manifold <b>14</b>.

p-0037A schematic view of the marine engine exhaust system <b>10</b> of <figref idrefs="DRAWINGS">FIG. 1</figref> is shown in <figref idrefs="DRAWINGS">FIG. 2</figref>. The first and second manifolds <b>12</b> and <b>14</b> function to transport the first gas <b>18</b> and second gas <b>24</b> therefrom without the presence of cooling water mixed with the gases <b>18</b> and <b>24</b>. The first gas <b>18</b> is transferred from the first manifold <b>12</b> into a first conduit <b>52</b>. In a similar fashion, the second gas <b>24</b> is transferred from the second manifold <b>14</b> into a second conduit <b>58</b>. The first conduit <b>52</b> and second conduit <b>58</b> may be defined in a first corner <b>16</b> and second corner <b>22</b>, respectively, in accordance with one embodiment of the present invention. The first conduit <b>52</b> and second conduit <b>58</b> are in fluid communication with a third conduit <b>64</b>. The third conduit <b>64</b> may be located in a crossover <b>28</b> that is connected to an end of the first corner <b>16</b> and second corner <b>22</b>. The first gas <b>18</b> can exit the first conduit <b>52</b> of the first corner <b>16</b> and enter the third conduit <b>64</b> of the crossover <b>28</b> in the downstream direction of flow. The second gas <b>24</b> in second conduit <b>58</b> of the second corner <b>22</b> can also exit therefrom into the third conduit <b>64</b> of the crossover <b>28</b> in the downstream direction of flow.

p-0038As the first gas <b>18</b> and second gas <b>24</b> are hot exiting the cylinders of the engine <b>46</b>, cooling fluid <b>32</b> is present in order to cool various components of the marine engine exhaust system <b>10</b>. As stated, the cooling fluid <b>32</b> is water in the exemplary embodiment shown in <figref idrefs="DRAWINGS">FIG. 2</figref>. The cooling fluid <b>32</b> is transferred by way of by-pass line <b>92</b> through port <b>34</b> and into a crossover cooling fluid passageway <b>30</b> of the crossover <b>28</b>. The cooling fluid <b>32</b> then proceeds to fill up the crossover cooling fluid passageway <b>30</b> and may do so upon filling from the bottom to the top of the crossover cooling fluid passageway <b>30</b>. This may be the case as the cooling fluid <b>32</b> will attempt to find the low point of the crossover cooling fluid passageway <b>30</b> first due to gravity.

p-0039Cooling fluid <b>32</b> then proceeds to flow into the first cooling fluid passageway <b>56</b> and the second cooling fluid passageway <b>62</b> from the crossover cooling fluid passageway <b>30</b>. When corners <b>16</b> and <b>22</b> are used, the first cooling fluid passageway <b>56</b> is a first corner cooling fluid passageway <b>20</b> and the second cooling fluid passageway <b>62</b> is a second corner cooling fluid passageway <b>26</b>. The cooling fluid <b>32</b> flows in the direction from the crossover cooling fluid passageway <b>30</b> to the first manifold <b>12</b> in the first cooling fluid passageway <b>56</b>. Similarly, the cooling fluid <b>32</b> flows in the direction from the crossover cooling fluid passageway <b>30</b> to the second manifold <b>14</b> in the second cooling fluid passageway <b>62</b>. Cooling fluid <b>32</b> exits the first cooling fluid passageway <b>56</b> into line <b>98</b>, and cooling fluid <b>32</b> exits the second cooling fluid passageway <b>62</b> into line <b>100</b>.

p-0040Cooling fluid <b>32</b> in line <b>98</b> is designated as cooling water <b>66</b> while cooling fluid <b>32</b> in line <b>100</b> is designated as cooling water <b>68</b>. Cooling water <b>66</b> flows through port <b>88</b> and into the third conduit <b>64</b> to merge with the first gas <b>18</b>. In a similar manner, cooling water <b>68</b> flows through a port <b>90</b> and merges with the second gas <b>24</b> in the third conduit <b>64</b>. These merged streams are represented by double arrows in <figref idrefs="DRAWINGS">FIG. 2</figref>. Cooling water <b>66</b> can merge with first gas <b>18</b>, and cooling water <b>68</b> can merge with second gas <b>24</b> before the first gas <b>18</b> and second gas <b>24</b> merge with one another. A combined stream <b>82</b> of the first gas <b>18</b>, second gas <b>24</b>, cooling water <b>66</b> and cooling water <b>68</b> can be formed and can be transferred through a hose <b>94</b> to a desired discharge point. This combined stream <b>82</b> is shown as a triple arrow. Introduction of the cooling water <b>66</b> and <b>68</b> before merging of the first gas <b>18</b> and second gas <b>24</b> functions to condense and cool the first gas <b>18</b> and second gas <b>24</b> and in turn reduces backpressure on the engine <b>46</b>. Although shown as merging with the first gas <b>18</b> and second gas <b>24</b>, it is to be understood that other arrangements are possible in which cooling water <b>66</b> and <b>68</b> merges with the first gas <b>18</b> and second gas <b>24</b> after the two gases merge with one another. Further, additional embodiments are also possible in which cooling water <b>66</b> and <b>68</b> does not merge with the first gas <b>18</b> and second gas <b>24</b>. It is to be understood that the merging scheme shown is but one possible embodiment and that other are possible.

p-0041Cooling water <b>66</b> and <b>68</b> that flows through ports <b>88</b> and <b>90</b> can be of any amount. For example, all of the cooling water discharged in the marine engine exhaust system <b>10</b> in the described circuit can flow through ports <b>88</b> and <b>90</b>. Alternatively, the cooling water <b>66</b> and <b>68</b> may be transferred through ports <b>88</b> and <b>90</b> in a mist form. Here, the additional cooling water <b>66</b> and <b>68</b> can be transferred to a downstream location for disposal from the system <b>10</b>. This downstream location may feature mixing with the combined stream <b>82</b> or may be discharged separate from the gases <b>18</b> and <b>24</b> and any previous misted cooling water <b>66</b> or <b>68</b>.

p-0042Referring now to both <figref idrefs="DRAWINGS">FIGS. 1 and 2</figref>, the marine engine exhaust system <b>10</b> is arranged so that the crossover <b>28</b> is located at a position that is generally vertically below the first corner <b>16</b> and second corner <b>22</b>. In this regard, cooling water <b>66</b> and <b>68</b> that enters the crossover <b>28</b> will first fill from the bottom of the crossover cooling fluid passageway <b>30</b> to the top due to gravity acting on the cooling water <b>66</b> and <b>68</b> upon entering the crossover cooling fluid passageway <b>30</b>. Upon filling the crossover cooling fluid passageway <b>30</b>, the cooling water <b>66</b> and <b>68</b> will then proceed to fill the vertically lowest portions of the first and second corner cooling fluid passageways <b>20</b> and <b>26</b>. The cooling water <b>66</b> and <b>68</b> fills the first and second corner cooling fluid passageways <b>20</b> and <b>26</b> from their vertically lowest portions to their vertically highest portions. The cooling water <b>66</b> and <b>68</b> can exit the first and second corner cooling fluid passageways <b>20</b> and <b>26</b> into lines <b>98</b> and <b>100</b> through ports that can be located at the vertically highest points of the first and second corner cooling fluid passageways <b>20</b> and <b>26</b>. It is to be understood, however, that in other embodiments the lines <b>98</b> and <b>100</b> can be provided cooling water <b>66</b> and <b>68</b> through ports that are not at the vertically highest portions of the first and second corner cooling fluid passageways <b>20</b> and <b>26</b>. Cooling water <b>66</b> and <b>68</b> fills the conduits <b>52</b>, <b>58</b> and <b>64</b> from their vertically lowest positions to their vertically highest positions. This method of filling the conduits <b>52</b>, <b>58</b> and <b>64</b> acts to push air pockets therefrom so that the passageways <b>20</b>, <b>26</b> and <b>30</b> are essentially completely filled with cooling water <b>66</b> and <b>68</b>. As such, air pockets are not present in the passageways <b>20</b>, <b>26</b> and <b>30</b> and associated hot spots are not present on the first corner <b>16</b>, second corner <b>22</b> and crossover <b>28</b>.

p-0043<figref idrefs="DRAWINGS">FIG. 3</figref> is a cross-sectional view of the corners <b>16</b> and <b>22</b> and the crossover <b>28</b>. The first corner cooling fluid passageway <b>20</b> is shown as jacketing a first gas passageway <b>54</b> through which the first gas <b>18</b> travels. In a similar manner, the second corner cooling fluid passageway <b>26</b> jackets a second gas passageway <b>60</b> through which the second gas <b>24</b> flows. The crossover cooling fluid passageway <b>30</b> jackets portions of both the first and second gas passageways <b>54</b> and <b>60</b>. the fluid passageways <b>20</b>, <b>26</b> and <b>30</b> can be arranged in various ways in accordance with other exemplary embodiments. For example, the fluid passageways <b>20</b>, <b>26</b> and <b>30</b> can be provided so as to surround only one side of the first and second gas passageways <b>54</b> and <b>60</b> in other arrangements.

p-0044The crossover <b>28</b> is a separate component that is attached to an end of the first corner <b>16</b> and second corner <b>22</b>. Other arrangements are possible in which these components can be a single unitary piece or may be separate elements that are attached to one another. Also shown in <figref idrefs="DRAWINGS">FIG. 3</figref> is an arrangement in which the first and second corner cooling fluid passageways <b>20</b> and <b>26</b> are placed into fluid communication with the crossover cooling fluid passageway <b>30</b>. Other arrangements are also possible. For example, hoses may be used in order to “jump” the cooling water <b>66</b> and <b>68</b> from the crossover cooling fluid passageway <b>30</b> to the first and second corner cooling fluid passageways <b>20</b> and <b>26</b> to avoid the points of connection between the crossover <b>28</b> and the first and second corners <b>16</b> and <b>22</b>. The port <b>34</b> in <figref idrefs="DRAWINGS">FIG. 3</figref> is shown as being located generally at the top of the crossover <b>28</b> such that cooling fluid <b>32</b> from the by-pass line <b>92</b> enters the top of the crossover cooling fluid passageway <b>30</b>. With such an arrangement, cooling fluid <b>32</b> will still fall to the bottom of the crossover cooling fluid passageway <b>30</b> due to gravity in order to fill this passageway from the bottom to the top. In other arrangements, port <b>34</b> can be located generally at the bottom of the crossover cooling fluid passageway <b>30</b> if desired.

p-0045A schematic circuit view of an additional exemplary embodiment of the marine engine exhaust system <b>10</b> is shown in <figref idrefs="DRAWINGS">FIG. 4</figref>. The engine <b>46</b> onto which the marine engine exhaust system <b>10</b> is employed is a twin head eight cylinder engine. The first and second manifolds <b>12</b> and <b>14</b> along with the first and second corners <b>16</b> and <b>22</b> may be constructed as previously described with respect to the exemplary embodiment of <figref idrefs="DRAWINGS">FIG. 1</figref> and a repeat of their possible design configurations is not necessary. Catalysts <b>36</b> and <b>42</b> along with associated oxygen sensors <b>38</b>, <b>40</b>, <b>41</b> and <b>45</b> may also be included as previously discussed above and need not be repeated here. The exemplary embodiment shown in <figref idrefs="DRAWINGS">FIG. 4</figref> employs a cooling fluid <b>32</b> that is antifreeze. As such, the marine engine exhaust system <b>10</b> in <figref idrefs="DRAWINGS">FIG. 4</figref> is commonly known as a fresh water system. Cooling fluid <b>32</b> flows through and cools the manifolds <b>12</b> and <b>14</b>. The cooling fluid <b>32</b>, which again is antifreeze in this system, exits manifold <b>12</b> into line <b>102</b> and exits manifold <b>14</b> into line <b>104</b>. Lines <b>102</b> and <b>104</b> merge to form line <b>106</b> through which the cooling fluid <b>32</b> is transferred.

p-0046Cooling fluid <b>32</b> enters the crossover cooling fluid passageway <b>30</b> through port <b>34</b> and proceeds to fill the crossover cooling fluid passageway <b>30</b> from the bottom up due to gravity. The cooling fluid <b>32</b> then flows into the first and second cooling fluid passageways <b>56</b> and <b>62</b> in a manner similar to that previously discussed with respect to the exemplary embodiment in <figref idrefs="DRAWINGS">FIG. 1</figref>. The arrangement of the marine engine exhaust system <b>10</b> in <figref idrefs="DRAWINGS">FIG. 4</figref> is made so as to reduce hot spots on the corners <b>16</b> and <b>22</b> and crossover <b>28</b> and a repeat of this information is not necessary. Cooling fluid <b>32</b> enters line <b>108</b> upon exiting the first cooling fluid passageway <b>56</b>. Cooling fluid <b>32</b> likewise exits the second cooling fluid passageway <b>62</b> and enters line <b>110</b>. Lines <b>108</b> and <b>110</b> merge to form line <b>112</b> through which the combined cooling fluid <b>32</b> flows.

p-0047A heat exchanger <b>44</b> is present in the exemplary embodiment of <figref idrefs="DRAWINGS">FIG. 4</figref>. The cooling fluid <b>32</b> flowing through line <b>112</b> is hot as it has traveled through the engine <b>46</b>, manifolds <b>12</b> and <b>24</b>, first corner <b>16</b>, second corner <b>22</b> and crossover <b>28</b> which are generally hot. The heat exchanger <b>44</b> receives water from the body of water <b>96</b> into which the watercraft rests such as a lake, river or ocean. The water received by the heat exchanger <b>44</b> is thus generally cool. Heat from the cooling fluid <b>32</b> in line <b>112</b> is transferred into the water in line <b>114</b> in the heat exchanger <b>44</b>. The warmed water in line <b>114</b> then exits the heat exchanger <b>44</b> and is split into cooling water <b>66</b> and cooling water <b>68</b> which flows through ports <b>88</b> and <b>90</b> respectively. Cooling water <b>66</b> is merged with the first gas <b>18</b> and cooling water <b>68</b> is merged with the second gas <b>24</b> in a manner previously described with respect to the exemplary embodiment in <figref idrefs="DRAWINGS">FIG. 1</figref>. As such, a repeat of this arrangement is not needed.

p-0048Cooling fluid <b>32</b> is thus cooled upon traveling through and exiting the heat exchanger <b>44</b>. The cooled cooling fluid <b>32</b> is then transferred to the engine <b>46</b> in order to cool various components thereof. Subsequently, the cooling fluid <b>32</b> is transferred into the first manifold <b>12</b> and second manifold <b>14</b> and acts to cool these components before being transferred into lines <b>102</b> and <b>104</b>. The aforementioned cycle thus repeats itself. As with the exemplary embodiment in <figref idrefs="DRAWINGS">FIG. 1</figref>, the combined stream <b>82</b> of first gas <b>18</b>, second gas <b>24</b>, cooling water <b>66</b> and cooling water <b>68</b> can be transferred by way of hose <b>94</b> to a desired location to be removed from the watercraft.

p-0049A further exemplary embodiment of the marine engine exhaust system <b>10</b> is shown in <figref idrefs="DRAWINGS">FIG. 5</figref>. This exemplary embodiment is similar to the one previously described with respect to <figref idrefs="DRAWINGS">FIG. 4</figref> with the addition of certain elements such as an elbow <b>48</b> and riser <b>50</b>. As with previous embodiments, the marine engine exhaust system <b>10</b> includes a pair of manifolds <b>12</b> and <b>14</b> with catalysts <b>36</b> and <b>42</b>. The system <b>10</b> is a fresh water system in which antifreeze is used as the cooling fluid <b>32</b>. <figref idrefs="DRAWINGS">FIG. 6</figref> is a schematic circuit view of the marine engine exhaust system <b>10</b>. Certain elements of system <b>10</b> are arranged in a manner similar to those previously discussed and as such a repeat of this information is not necessary. For example, the cooling fluid <b>32</b> flows from the crossover cooling fluid passageway <b>30</b> and into the first and second cooling fluid passageways <b>56</b> and <b>62</b>.

p-0050The marine engine exhaust system <b>10</b> in <figref idrefs="DRAWINGS">FIG. 6</figref> includes a crossover <b>30</b> through which the first gas <b>18</b> and second gas <b>24</b> flow without mixing with one another or with cooling water <b>66</b> and <b>68</b>. Instead, the two separate streams of gas <b>18</b> and <b>24</b> flow through the riser <b>50</b> and into elbow <b>48</b>. Cooling water in line <b>114</b> from the heat exchanger <b>44</b> enters the riser <b>50</b> through port <b>86</b>. As such, cooling water from line <b>114</b> does not enter the crossover <b>28</b>. Cooling water from line <b>114</b> flows into elbow <b>48</b> and is designated as cooling water <b>66</b> and cooling water <b>68</b>. Cooling water <b>66</b> merges with the first gas <b>18</b> and cooling water <b>68</b> merges with the second gas <b>24</b> before the first gas <b>18</b> and second gas <b>24</b> merge with one another. These combined streams are shown as double arrows in <figref idrefs="DRAWINGS">FIG. 6</figref>. This arrangement functions to condense and cool the first and second gas <b>18</b> and <b>24</b> which reduces backpressure on the engine <b>46</b>. A combined stream <b>82</b> of the first gas <b>18</b>, second gas <b>24</b>, cooling water <b>66</b> and cooling water <b>68</b> is subsequently formed and expelled from the system <b>10</b>. Combined stream <b>82</b> is shown as a triple arrow in <figref idrefs="DRAWINGS">FIG. 6</figref>.

p-0051A cross-sectional view of the first corner <b>16</b>, second corner <b>22</b> and crossover <b>28</b> is shown in <figref idrefs="DRAWINGS">FIG. 7</figref>. As shown, the first corner cooling fluid passageway <b>20</b> completely surrounds the first gas <b>18</b>, and the second corner cooling fluid passageway <b>26</b> surrounds the second gas <b>24</b>. The passageways <b>20</b> and <b>26</b> are placed into fluid communication with the crossover cooling fluid passageway <b>30</b> in a manner similar to that previously discussed with respect to the exemplary embodiment in <figref idrefs="DRAWINGS">FIG. 1</figref>. However, it is to be understood that the passageways <b>20</b> and <b>26</b> can be placed into fluid communication with crossover cooling fluid passageway <b>30</b> in a variety of manners such as those described above with reference to the exemplary embodiment of <figref idrefs="DRAWINGS">FIG. 1</figref>. A wall <b>116</b> is present in order to prevent the first gas <b>18</b> and second gas <b>24</b> from mixing in the crossover <b>28</b>. Port <b>34</b> can be generally located at either the top or bottom of the crossover <b>28</b> to allow cooling fluid <b>32</b> to enter and fill the crossover cooling fluid passageway <b>30</b> from the bottom to the top. Cooling water <b>66</b> and <b>68</b> does not mix with the first gas <b>18</b> and second gas <b>24</b> in the crossover <b>28</b>. The first corner <b>16</b> and second corner <b>22</b> are separate components that are attached to the crossover <b>28</b>. However, in other embodiments these components may be either one single piece or made of two separate pieces. Various attributes of the crossover <b>28</b>, first corner <b>16</b> and second corner <b>22</b> can be provided in a manner similar to that discussed above with reference to previous exemplary embodiments and a repeat of this information is not necessary.

p-0052Cooling fluid <b>32</b> enters the crossover cooling fluid passageway <b>30</b> through port <b>34</b> and proceeds to fill the crossover cooling fluid passageway <b>30</b> from the bottom up due to gravity. The cooling fluid <b>32</b> then flows into the first and second cooling fluid passageways <b>56</b> and <b>62</b> in a manner similar to that previously discussed with respect to the exemplary embodiment in <figref idrefs="DRAWINGS">FIG. 1</figref>. The arrangement of the marine engine exhaust system <b>10</b> in <figref idrefs="DRAWINGS">FIG. 6</figref> is made to reduce hot spots on the corners <b>16</b> and <b>22</b> and crossover <b>28</b> and a repeat of this information is not necessary. Although described as cooling the entire lengths of the first corner <b>16</b>, second corner <b>22</b> and crossover <b>28</b> it is to be understood that the entire lengths of these elements need not be cooled by the cooling fluid <b>32</b> in accordance with other embodiments.

p-0053With reference now to <figref idrefs="DRAWINGS">FIGS. 5 and 8</figref>, the marine engine exhaust system <b>10</b> is shown as employing elbow <b>48</b> and riser <b>50</b>. The first gas <b>18</b> and second gas <b>24</b> exit the crossover <b>28</b> and flow into one or more risers <b>50</b>. The risers <b>50</b> function to allow the first and second gases <b>18</b> and <b>24</b> to be transported upwards in the vertical direction. Upwards elevation of the gases <b>18</b> and <b>24</b> may be necessary in order to discharge the gases <b>18</b> and <b>24</b> over a wall or other structure of the watercraft. A wall <b>118</b> is present in riser <b>50</b> in order to keep the first gas <b>18</b> separate from the second gas <b>24</b> as they flow therethrough. If additional risers <b>50</b> are stacked on top of one another to achieve a desired height the additional risers <b>50</b> can also include the wall <b>118</b> to keep the gases <b>18</b> and <b>24</b> separate through their transfer length.

p-0054An elbow <b>48</b> is connected to the riser <b>50</b> and discharges the exhaust gases <b>18</b> and <b>24</b> from a tip <b>72</b> into the body of water in which the watercraft is deployed or into a hose <b>94</b> (not shown). The riser <b>50</b> is connected to an inlet of the elbow <b>48</b>. The elbow <b>48</b> includes a wall <b>70</b> throughout a portion of its length which acts to maintain the gases <b>18</b> and <b>24</b> separate throughout this portion of the elbow <b>48</b>. An inlet <b>120</b> through which cooling water <b>66</b> is dispensed is in communication with the first gas passageway <b>54</b> of the first conduit <b>52</b>. Inlet <b>122</b> through which cooling water <b>68</b> can be transferred is in communication with the second gas passageway <b>60</b> of the second conduit <b>58</b>. Cooling water <b>66</b> is merged with the first gas <b>18</b> to form a combined stream, and cooling water <b>68</b> is mixed with the second gas <b>24</b> to likewise form a combined stream. At this point, the wall <b>70</b> acts to maintain the gases <b>18</b> and <b>24</b> separate from one another. As such, cooling water <b>66</b> and <b>68</b> is mixed with the gases <b>18</b> and <b>24</b> before the gases <b>18</b> and <b>24</b> are mixed with one another. The addition of cooling water <b>66</b> and <b>68</b> before the gases <b>18</b> and <b>24</b> are merged with one another acts to cool the individual gas streams <b>18</b> and <b>24</b> and reduce backpressure on the engine <b>46</b> as previously discussed. The inlets <b>120</b> and <b>122</b> may be located at the top of the conduits <b>52</b> and <b>58</b> so that the cooling water <b>66</b> and <b>68</b> may be dispensed through a larger amount of the first and second gases <b>18</b> and <b>24</b> to increase the amount of cooling.

p-0055The combined streams can be merged with one another to form a combined stream <b>82</b> of cooling water <b>66</b> and <b>68</b> and gases <b>18</b> and <b>24</b>. Combined stream <b>82</b> exits the elbow <b>48</b> from the tip <b>72</b>. The gases <b>18</b> and <b>24</b> can be maintained separate from the cooling water <b>66</b> and <b>68</b> until the tip <b>72</b> of the elbow <b>48</b> in order to maximize the distance between the introduction of the cooling water <b>66</b> and <b>68</b> into the conduits <b>52</b> and <b>58</b> and the manifolds <b>12</b> and <b>14</b>. This configuration helps to keep the cooling water <b>66</b> and <b>68</b> remote from the catalysts <b>36</b> and <b>42</b> and associated oxygen sensors <b>38</b>, <b>40</b>, <b>41</b> and <b>45</b> and the engine <b>46</b> to prevent damage thereto. In this configuration, water will have to transfer through reversion a great distance thus reducing the odds of water damaging the aforementioned components.

p-0056Although described and shown as mixing at the tip <b>72</b>, the combined stream of first gas <b>18</b> and cooling water <b>66</b> and the combined stream of second gas <b>24</b> and cooling water <b>68</b> need not mix at this location to form the combined stream <b>82</b> in other embodiments. For example, the elbow <b>48</b> may be configured so that the combined streams are sprayed from the tip <b>72</b> to an area outside of the watercraft or into a hose <b>94</b> (not shown). In this regard, the combined streams may either not merge with one another to form the combined stream <b>82</b> or may do so at a location away from the elbow <b>48</b>.

p-0057The marine engine exhaust system <b>10</b> is designed so that the direction of flow of the first gas <b>18</b> and second gas <b>24</b> is not in the same direction as the cooling fluid <b>32</b> used to cool the first and second gases <b>18</b> and <b>24</b> in the conduits <b>52</b> and <b>58</b>. For example, referring to <figref idrefs="DRAWINGS">FIG. 2</figref>, the first gas <b>18</b> is shown as having a direction of flow <b>74</b> that is not in the same direction as the direction of flow <b>78</b> of the cooling water <b>66</b> in the first conduit <b>52</b>. In fact, the direction of flow <b>74</b> is opposite to that of the direction of flow <b>78</b>. However, it is to be understood that other embodiments are possible in which the directions of flow <b>74</b> and <b>78</b> are not opposite to one another but are only different from one another. In a similar vein, the direction of flow <b>76</b> of the second gas <b>24</b> is not the same as, and is in fact opposite to, the direction of flow <b>80</b> of the cooling water <b>68</b> in the second conduit <b>58</b>. Again, although shown as being completely opposite from one another the directions of flow <b>76</b> and <b>80</b> may only be different from one another in other embodiments. The directions of flow <b>74</b> and <b>78</b> may be the same as or different from one another in the third conduit <b>64</b>. Similarly, the directions of flow <b>76</b> and <b>80</b> may be the same as or different from one another in the third conduit <b>64</b>. Other disclosed embodiments are configured in a similar manner.

p-0058<figref idrefs="DRAWINGS">FIGS. 4 and 6</figref> disclose fresh water systems in which the cooling fluid <b>32</b> is antifreeze instead of cooling water <b>66</b> and <b>68</b>. However, the direction of flow <b>74</b> of the first gas <b>18</b> is different from the direction of flow <b>78</b> of the cooling fluid <b>32</b> in the first conduit <b>52</b>. Likewise, the direction of flow <b>76</b> of the second gas <b>24</b> is different from the direction of flow <b>80</b> of the cooling fluid <b>32</b> in the second conduit <b>58</b>. The fluid flow of the embodiments in <figref idrefs="DRAWINGS">FIGS. 4 and 6</figref> is arranged in a manner as described above with respect to the version in <figref idrefs="DRAWINGS">FIG. 1</figref> with the caveat that the cooling fluid <b>32</b> is antifreeze instead of water.

p-0059The aforementioned embodiments have been described as having a first corner <b>16</b> that is incorporated into a first conduit <b>52</b> and has having a second corner <b>22</b> that is incorporated into a second conduit <b>58</b>. Further, the presence of a crossover <b>28</b> has been mentioned in all discussed embodiments. It is to be understood that other exemplary embodiments of the marine engine exhaust system <b>10</b> exist which do not include a first corner <b>16</b>, second corner <b>22</b> or crossover <b>28</b>. In these embodiments, the first conduit <b>52</b> and second conduit <b>58</b> can be configured into different types of components. Further, the third conduit <b>64</b> can be a different type of component and need not have a crossover <b>28</b> or elbow <b>48</b> incorporated therein.

p-0060The present application involves subject matter that relates to that disclosed in U.S. patent application Ser. No. 11/729,671 entitled, “Marine Engine Exhaust System” filed Mar. 29, 2007. The entire contents of U.S. patent application Ser. No. 11/729,671 are incorporated by reference herein in their entirety for all purposes.

p-0061While the present invention has been described in connection with certain preferred embodiments, it is to be understood that the subject matter encompassed by way of the present invention is not to be limited to those specific embodiments. On the contrary, it is intended for the subject matter of the invention to include all alternatives, modifications and equivalents as can be included within the spirit and scope of the following claims.